public function toXMLString()
 {
     $str = '';
     $str .= parent::toXMLString();
     if ($this->DoExpressCheckoutPaymentRequestDetails != null) {
         $str .= '<ebl:DoExpressCheckoutPaymentRequestDetails>';
         $str .= $this->DoExpressCheckoutPaymentRequestDetails->toXMLString();
         $str .= '</ebl:DoExpressCheckoutPaymentRequestDetails>';
     }
     if ($this->ReturnFMFDetails != null) {
         $str .= '<urn:ReturnFMFDetails>' . PPUtils::escapeInvalidXmlCharsRegex($this->ReturnFMFDetails) . '</urn:ReturnFMFDetails>';
     }
     return $str;
 }
 public function toXMLString()
 {
     $str = '';
     $str .= parent::toXMLString();
     if ($this->DoExpressCheckoutPaymentRequestDetails != null) {
         //prop is not a collection
         //prop is complex
         //prop is not enum
         //does not contain attribute or is attribute
         $str .= '<ebl:DoExpressCheckoutPaymentRequestDetails>';
         $str .= $this->DoExpressCheckoutPaymentRequestDetails->toXMLString();
         $str .= '</ebl:DoExpressCheckoutPaymentRequestDetails>';
     }
     if ($this->ReturnFMFDetails != null) {
         //prop is not a collection
         //prop not complex
         //prop is not value
         $str .= '<urn:ReturnFMFDetails>' . $this->ReturnFMFDetails . '</urn:ReturnFMFDetails>';
     }
     return $str;
 }